A storage system includes a plurality of host computers, a plurality of fiber channel switches (FC switches), a plurality of physical storage devices, and a plurality of storage virtualization devices, for example. A host computer outputs an instruction to write data to a storage virtualization device. The host computer is connected to a fiber channel switch, and the instruction that is output by the host computer is reported to the fiber channel switch. The fiber channel switch is connected to a plurality of storage virtualization devices. The fiber channel switch transmits the received instruction to one of the plurality of storage virtualization devices. Each of the storage virtualization devices operates as a virtual storage device in combination with some or all storage areas in a plurality of physical storage devices. Each of the storage virtualization devices provides a virtual storage device accessible by the host computers. After being accessed by the host computer, the storage virtualization device accesses the storage area in the physical storage device which corresponds to an access area in the storage virtualization device.
A concentration of accesses on one storage virtualization device is not desirable in a storage system since this causes a delay in processing. Thus, for example, a fiber channel switch assigns accesses from host computers in a round robin manner to a plurality of storage virtualization devices. The accesses are not concentrated on one storage virtualization device because of the round robin assignment.
As a technology on a fiber channel switch, there exists a technology which permits associating of a virtual port with a plurality of physical ports in a fiber channel switch so as to control the virtual port as a transmission destination (see Patent Document 1, for example).
As a technology relating to load-balancing, a technology exists which permits collecting of various pieces of performance data in physical storage devices and computing of a set of overall metrics so as to load balance between the physical storage devices (see Patent Document 2, for example).
Patent Document 1: Japanese Laid-open Patent Publication No. 2011-76582
Patent Document 2: Japanese National Publication of International Patent Application No. 2008-521140